1. Field of the Invention
This invention relates to an ink jet recording head for elastically deforming an elastic plate forming a pressure generation chamber by a piezoelectric vibrator and jetting ink in the pressure generation chamber as an ink drop through a nozzle opening and more particularly to a structure of a flow passage formation substrate.
2. Description of the Related Art
An ink jet recording head is designed for pressurizing a pressure generation chamber communicating with a common ink chamber and a nozzle opening by pressure generation means, such as a heating element provided in the pressure generation chamber or a piezoelectric vibrator provided so as to be able to deform a part of the pressure generation chamber, for jetting ink drops.
For example, JP-A-9-123448 proposes an ink jet recording head wherein a substrate is formed on both faces with first and second pressure generation chambers as concaves, wherein each pressure generation chamber is provided with first and second ink supply ports as slightly narrowed concaves communicating with a reservoir, and wherein a nozzle communication hole in the form of a through hole is made in an area opposed to the nozzle opening.
In this type of recording head, the pressure generation chamber volume can be made small and minute ink drops fitted to graphics print can be jetted. In addition, the through hole occupying the substrate is small and rigidity can be provided, thus the substrate can be made thin and it is possible to shorten the etching time and reduce material costs.
However, as shown in FIG. 18, since substrate 100 is formed on both faces with first and second flat pressure generation chambers 41 (not shown) and 103, when a nozzle opening 103 is sealed with a cap and negative pressure is made to act on the nozzle opening 103 from the outside for forcibly discharging ink for recovering ink drop jet performance, the flow velocity of ink flowing into the pressure generation chamber 41, 102 from reservoir 104 easily decreases. Thus, bubbles easily accumulate particularly in the pressure generation chamber 41 on the piezoelectric vibrator 105 side. Since the bubbles absorb pressure applied by the piezoelectric vibrator, as is known, the ink drop jet capability lowers, degrading print quality. In FIG. 18, numerals 106 and 107 denote first and second ink supply ports.
Since the pressure generation chambers become shallow as compared with the case where the pressure generation chamber is formed as a single chamber, flow passage resistance of the pressure generation chamber is large and ink supply from the reservoir to the pressure generation chamber is delayed, slowing down drive speed.